General description

  • Hydatids are the cystic stage of the dog tapeworm Echinococcus granulosus.
  • The tapeworm is tiny, only 3 - 6 mm long and lives in the intestines of dogs.
  • Hydatids do not affect sheep health or production on farm.
  • Hydatid cysts can be fatal in humans. Tapeworm cysts can be found in the liver or lungs (the two most common sites), the brain, kidneys, spleen, heart or other parts of the body. A heavily infested organ may fail or a cyst may rupture and cause a life-threatening allergic reaction.


  • The larval cyst forms in intermediate host animals such as sheep. Affected sheep organs are condemned at slaughter. 

Clinical signs

  • Clinical signs in live sheep are rare, unless the cyst is in the brain, when the animal’s movement may be affected. At slaughter infected carcasses may be trimmed or condemned.


  • Cysts cannot be detected on live animals but are readily seen by examining the animal at the abattoir.
  • Cysts can occur on the brain, lungs or liver.



  • There is no effective treatment for sheep with hydatid cysts.


  • Monthly worming of farm dogs (with a product that contains the active ingredient praziquantel) , restricting them from access to offal will help prevent hydatids.

Learn more

Fact Sheet - Hydatids

How can you be affected by Hydatids?

Hydatids - A Disease of Dogs that Affects People

Hydatids they are still out there